Prussian blue caged in spongiform adsorbents using diatomite and carbon nanotubes for elimination of cesium

► Prussian blue was sealed in cavities of diatomite using carbon nanotubes. ► The caged Prussian blue after being permanently immobilized in polyurethane spongy showed a 167 mg/g capability for absorbing cesium. ► Cesium elimination was accomplished by simply adding the Prussian-blue based spongiform adsorbent to radioactive water.